NEW YORK (AP) — A new scientific discovery has pushed back the known history of the plague by roughly 200 years, with researchers now tracing the disease’s earliest outbreaks to approximately 5,500 years ago.
The plague has afflicted human populations for millennia, most famously devastating Europe’s population during the 14th century in what became known as the Black Death. While the disease is rare today, it still exists and can be treated with antibiotics.
“To understand our own history, we believe that understanding the history of plague is extremely important,” said study co-author Eske Willerslev, an evolutionary geneticist with the University of Copenhagen in Denmark.
Willerslev and a team of researchers examined remains from four burial sites near Lake Baikal in Siberia, searching for traces of the bacteria responsible for the plague. Their efforts turned up plague DNA in the teeth of 18 ancient hunter-gatherers.
Carbon dating of the bones revealed that the plague caused two separate outbreaks, with the earliest cases appearing around 5,500 years ago.
Researchers determined that the prehistoric version of the plague developed gradually and struck several small family groups. It is believed to have originated in marmots — large rodents native to the region — and spread to humans who consumed raw organs or handled infected animal hides while butchering them. The disease also passed between people through respiratory droplets from coughing and sneezing, according to the study’s authors.
A significant portion of those who perished were young children between the ages of 8 and 11. The study, published Wednesday in the journal Nature, noted that three young girls were buried together, two of whom were likely cousins. An aunt and nephew were also found in the same grave, while her niece was buried separately in another shared plot.
“People were around to bury the dead who knew who these people were when they were alive. And that’s a really human element to all of the scientific work,” said study co-author Ruairidh Macleod, who studies ancient DNA at the University of Oxford.
Researchers suggested that children may have faced greater danger because their immune systems were not fully developed.
The fact that multiple victims were found together indicates the prehistoric plague could cause both isolated cases and larger outbreaks, according to geneticist Aida Andrades Valtueña with the Max Planck Institute for Evolutionary Anthropology, who was not involved in the study.
The research also showed that this early form of the plague existed long before the bubonic plague strain that caused the Black Death in medieval Europe. Yet evidence suggests these earlier outbreaks were equally lethal, wiping out not just densely populated urban centers but also small, mobile hunter-gatherer communities.
Understanding this history can help scientists “understand the steps that the bacterium took to become the deadly pathogen we know today, and that can provide clues on how pathogens may emerge in the future,” Andrades Valtueña said in an email.
